Circuit breaker with arc restraining members in fluid supply passageways



June 26, 1956 P. L. TAYLOR ETAL CIRCUIT BREAKER WITH ARC RESTRAINING MEMBERS IN FLUID SUPPLY PASSAGEWAYS 4 Sheets-Sheet 1 Filed April 27, 1953 June 26, 1956 P. 1.. TAYLOR ETAL 2,752,459

CIRCUIT BREAKER WITH ARC RESTRAINING MEMBERS IN FLUID SUPPLY PASSAGEWAYS Filed April 27, 1953 4 Sheets-Sheet 2 //Z //3 SmzmXom //4 //5 592m 35" gawk/L //6 @WM 6. sum

was Yew/WM June 26, 1956 P. L TAYLOR ETAL 2,752,459

CIRCUIT BREAKER WITH ARC RESTRAINING MEMBERS IN FLUID SUPPLY PASSAGEWAYS 4 Sheets-Sheet 3 Filed April 27, 1953 June .26, 1956 P. L TAYLOR ETAL 2,752,459

CIRCUIT BREAKER WITH ARC RESTRAINING MEMBERS IN FLUID SUPPLY PASSAGEWAYS Filed April 27, 1953 4 Sheets-Sheet 4 limited States Patent 0 CIRCUIT BREAKER WITH ARC RESTRAINING MEMBERS IN FLUID SUPPLY PASSAGEWAYS Philip L. Taylor, Abington, and Arthur C. Kelle, Stougln ton, Mass., assignors to Allis-Chalmers Manufacturing Company, Milwaukee, Wis.

Application April 27, 1953, Serial No. 351,262

12 Claims. (Cl. 200-150) This invention relates to circuit interrupters and more particularly to arc extinguishing structures therefor. F

More specifically this invention relates to a novel structure for effecting the very rapid extinction of electric arcs drawn in circuit interrupters. This invention is ap-. plicable to the interruption of high voltagearcs such as those drawn in 287 kv. circuits but is also applicable on low voltage circuits.

Experience has demonstrated that a rapid lowering of the dielectric strength of an arc extinguishing fluid, such as oil, occurs after it impinges upon the arc stream. It is therefore desirable to eliminate such contaminated fluid as quickly as possible, and to subject the are stream to the action of fresh fluid of high dielectric strength. The isolation or disconnection of a capacitance load by a circuit breaker in an alternating current system is subject to transient overvoltages, the magnitudes of which depend on the capacitance of the load, the voltage of the system, and the type of the circuit breaker. In isolating such a capacitance load, interruption at the first current zero in the arc of the leading current is readily eflected at a relatively small contact separation. In one-half cycle after the first current Zero, the voltage of the source has reversed to its crest value, and approximately double this voltage appears across the circuit breaker contacts as a circuit recovery voltage. Whether or not rest riking of the arc occurs depends on several factors, such as the type of the circuit breaker, including the speed and the magnitude of the separation of its contacts, the magnitude of the circuit recovery voltage, and the leading kva. of the load.

These circuit conditions are difiicult if not impossible to control. Therefore, restriking in most breakers must be expected especially under severe operating conditions, and the circuit interrupting structures must operate efficiently under such conditions.

In accordance with this invention, a new and improved circuit interruptin structure is provided in which an arc interrupter is immersed in arc extinguishing fluid. The interrupter comprises a pair of cooperating'contacts separable to draw an are. A barrier plate assembly comprising a plurality of contiguously disposed insulating plates defining a substantially enclosed arc passage is provided for confining the are along a major portion of its length. Some of the barrier plates comprise inlet plates providing a pair of diametrically positioned inlet passages on one level so that an incoming flow of fluid may pass through the inlet passages inwardly toward the arc substantially transversely thereto on opposite sides thereof. Dual purpose grid means are arranged across one inlet passage of a number of the inlet plates to restrict the flow c-f fluid through the inlet passages and to hold the are close to the longitudinal axis of the stack formed by the barrier plates. I

It is, therefore, one object of the present invention to provide a new and improved circuit interrupter arranged to draw at least two serially connected arcs in which the first arc .is subjected to un-ionized arc extinguishing fluid 2,752,459 Patented June 26, 1956 forcibly impelled into the arcing region at one or more points along the arc.

Another object of this invention is to provide a new and improved circuit interrupter arranged to draw an arc in which the arc is restrained at a plurality of points along the arc from moving out of a given are path.

A still further object of this invention is to provide a new and improved circuit breaker in which the arc subjected to a plurality of inwardly flowing streams of fluid under pressure is restrained from moving out of a pre determined path.

Objects and advantages other than those above set forth ill be apparent from the following description when read in connection with the accompanying drawings in which:

Fig. l is an elevational view partly in section of a circuit interrupter embodying the invention and shown in circuit closed position;

Fig. 2 is an enlarged sectional view through one of the interrupting devices shown in Fig. l and embodying the present invention;

Fig. 3 is an enlarged elevational view of the lower disk assembly shown in Fig. 2;

Fig. 4 is a top view of the disk assembly shown in Fig. 3;

Figs. 5 to 51, inclusive, are detailed views of the disks forming the assembly shown in Figs. 2, 3 and 4;

Fig. 52 is a modification of the disk shown in Fig. 29;

Fig. 53 is a cross section of Fig. 52 taken along the line A-A; and

Fig. 54 is a sectional view taken along the line 3-8 of Fig. 2.

Referring to the drawings by characters of reference, Fig. 1 illustrates an oil circuit breaker unit of the high voltage type such as that used in power transmission systems. Unit 1 is suspended from one line terminal of the circuit interrupter in a suitable tank 2 and submerged in a suitable insulating arc extinguishing fluid, such as oil. A conducting bridging bar 3 serves to connect electrically the arc extinguishing unit 1 with an identical unit 4 in a manner well known in the art. Supported on a cover 5 of the tank 2 are a pair of terminal bushings 6 and 7 (partially shown), to the lower ends of which are secured arc extinguishing units 1 and 4. The cross bar 4 is actuated reciprocably in the vertical direction by an insulating lift rod 8 to open and close the contacts of the arc extinguishing units 1 and 4.

Fig. 2 illustrates the internal construction of the arc extinguishing unit 1. Clamped to the lower end or a terminal bushing 6 is a conductive housing 11 which forms a conductive path between it and a movable contact 16. Contact 16 is arranged in a pressure chamber 431. In the closed circuit position, as shown in Fig. 2, the contact 16 engages an intermediate contact 13, the latter, in turn, engaging a rod shaped contact 14 secured to the extremity of the cross bar 3. Contact 14 is arranged in a pressure chamber 44. Contact 13 comprises two contact engaging surfaces. Contact 3.6 cooperates with one of the contact engaging surfaces to produce a first arc and contact 14 cooperates with the other of the contact engaging surfaces to produce a second are.

A plurality of rocking finger contacts 15 rest against the upper end of rod shaped pressure generating contact 16. Current is transferred from housing 11 to contact 16 through rocking finger contacts 15. This arrangement dispenses with braids or similar flexible conductors and also eliminates the necessity of the actuating means for contact 16 from carrying current. in other words, there is a complete and desirable segregation of the current carrying function and the contact operating or actuating function.

In the closed circuit position of the interrupting unit 1,

as shown in Figs. 1 and 2, the electric circuit therethrough comprises the terminal stud (not shown) in bushing 6, housing 11, finger contacts 15, rod contact 16, intermediate contact 13, movable interrupting contact 14, conducting cross bar 3, movable interrupting contact 14', and the right hand are extinguishing unit 4 as in housing 11 to the terminal stud (not shown) in bushing 7.

Contact 16 is actuated by a lever 17 having an oblong hole 18 in one end thereof and adapted to be rocked about a stud 19. A pin it) in rod 16 engages oblong hole 18 in lever 17. A cradle 20 is journaled to lever 17 by means of a pin 21 and biased downward by a spring 22. Cradle 20 supports a rod 23 for the operation of a piston pump 12. Cradle 20 is adapted to be operated by an insulating operating tube or rod 25 which in turn is operated by the cross bar 3 of the circuit breaker. When cross bar 3 and operating rod 25 are raised or lowered, the cradle 24 is simultaneously raised or lowered and rocks about pin 21 relative to lever 17 simultaneously with its raising or lowering movement. The circuit breaker unit 1 may employ contact-s 16 and 13 alone or in combination with spring actuated oil pump 12 for the interruption of line charging currents and such low value of inductive currents as are not efifectively interrupted by other types of devices.

A valve disk 27 is loosely mounted on rod 23 and biased against the piston 24 of pump 12 by a spring 28. Spring 28 is disposed between the valve disk 27 and a flange 29 secured to housing 11. The piston 24 is provided with a plurality of apertures 30 which form a passageway for oil flow under certain conditions between the upper and lower portions of the housing through piston 24. The apertures are controlled by disk 27. g

During a circuit closing operation of the interrupter, the bridging contact member or bar 3 forces the operating rod 25 upward. Operating rod 25 in its upward movement rotates arcing contact lever 17 counterclockwise to cause contact 16 to engage the contact surfaces of the fixed contact 13. Rod 25 in its upward movement to closed circuit position pushes rod 23 upward against the biasing action of the spring biased piston 24 of pump 12.

The are interrupting unit 1 utilizes two groups of barrier plate assemblies 35 and 36 of suitably shaped insulating plates which form part of the walls of the paths through which the arcs produced by contacts 16, 13 and 14 are drawn.

As shown in Fig. 2, an aperture 140 may be provided in the lower barrier plate of assembly 35 and plate 141 which separates the upper grid assembly 35 from the chamber 44 and particularly from the lower grid assembly 36. This aperture 149 may be omitted if it is desired to substantially completely isolate the upper chamber 41 from the lower chamber 44.

If aperture 149 is provided in plate 141 then the are drawn between the contacts 16 and 13 may be called a pressure generating arc and the are drawn between contacts 13 and 14 an interrupting arc. With aperture 140 in the lower barrier plate of assembly 35 and plate 141, piston 24 causes a first fiow of fluid under pressure through the passageway 37, through the passageway 142 extending across the barrier plates of assembly 35. The passageway 142 extending through the barrier plates also extends across the passageway 59 extending through the barrier plates longitudinally of the axis of the interrupter. Piston 24 also causes a second flow of fluid under pressure through passageway 37, aperture 140 in the lower barrier plate of assembly 35 and plate 141, chamber 44 and into the barrier plate assembly 36. The first blast of fluid under pressure cools and extinguishes the pressure generating arc and the second blast of fluid under pressure cools and extinguishes the interrupting arc.

Each interrupting unit is provided with two parallel cylindrical resistor assemblies 45. The upper end of each resistor assembly 45 is conductively connected to an electrostatic shield 46. Shield 46 is conductively connected to housing 11 which in turn is conductively connected tothe lower terminal end of the breaker bushing 6. The lower end of each resistor assembly 45 is conductively connected to the lower electrostatic shield 47. Shield 47 is conductively connected to an arcing electrode comprising a disk like member 48 through a conductive circuit comprising bolts 49, plate 50, bolts 51 and ring support 52.

The lower end of the arc interrupting chamber 44 com prises an insulating nozzle 55 forming an opening 56. The arcing electrode 48 is secured within chamber 44 between the lower end of the barrier plate assembly 35 and the opening 56.

When it is desired to open the electric circuit passing through the interrupter, or when overload conditions exist in the electric circuit controlled by the interrupter suitable operating mechanism (not shown) moves the insulating lift rod 8 to result in a downward movement of the conducting cross bar 3 and the movable contacts 14, E4.

The downward movement of cross bar 3 causes insulating operating rod 25 to rotate lever 1'7 clockwise about the pivot stud 19 to draw an are between contacts 16 and 13. Substantially simultaneously therewith or with a slight delay the-movable contact 14 separates from the intermediate or fixed contact 13 to draw an are between contacts 13 and 14. The downward movement of operating rod 25 causes the downward movement of piston 24 to move the oil within the pump cylinder 26. The oil, now under pressure within the pump cylinder 26 flows under pressure out of the cylinder 26 through passageway 37, through the barrier plate stack 35 transversely of the longitudinal axis of the arc extinguishing unit 1, through the passageway 38 into chamber 39 and through orifice 43 to the inside of tank 2.

During the interruption of low currents, the operating rod 25 moves downwardly at the same speed as the cross bar 3 to result in the lever 17 rotating clockwise about stud 19 to draw an are between contacts 16 and 13. The rod 23 and piston 24 follow the downward movement of operating rod 25. Valve disk 27 closes apertures 30 and moves the oil in cylinder 26 into passageway 37. This action occurs during the interruption of low currents.

During the interruption of high current arcs, the pres sure created by the are drawn between contacts i6 and 13 may prevent the downward movement of the piston 24 and this, in turn, halts the downward movement of the rod 23. The cradle 20 then separates from rod 23.

When the pressure subsides within the barrier plate assembly 35 oil under pressure within housing 26 flows out through barrier plate assembly 35 to flush the region Where the arc occurred between contacts 16 and 13. This scavaging action raises the dielectric strength of the oil in the barrier plate assembly 35 and prevents restriking between contacts 16 and 13 which would prolong the arcing time of the interrupter. it also prevents premature breakdown ofthe contact gap during an immediately following closing operation. The grid assembly 35 is particularly usefulin circuit breakers used to isolate a capacitive load of such capacitance and voltage that the voltage gradient across the arc interrupting contacts of the circuit breaker exceeds the dielectric strength between these contacts.

For efficient circuit breaker operation it is desirable to provide an arc extinguishing device adjacent the pressure generating arc-as well as the interrupting arc.

The downward movement of contact 14 draws an arc in the barrier plate stack assembly36 between'contact 14 and the fixed contact 13. The are drawn between contacts 13 and 14 breaks down a portion of the arc extinguishing liquid which surrounds the arc and saturates the barrier plate assembly 36.

' The barrier plate assembly 36 is spaced from the intermediate contact 13 so as to form the pressure generating chamber 44 adjacent the region of arc initiation. The disk assembly 36 has a central aperture forming a contact passageway 32 through which the contact 14 moves to open and close the power circuit. Surrounding the contact passageway 32 are multiple helical passageways beginning at the pressure chamber 44 and extending through the disk assembly 36 to the space external of interrupting device 1. These helical passageways are shown as formed by means of disks 70 to 116 which are shown respectively in Figs. to 51. The disks 73 to 116 have substantially butterfly shaped cut out portions extending from the central aperture forming the contact passageway 32, with the openings into a fluid supply passageway 120 being of a width less than the width of the passageway 32.

To clarify the disclosure as to these helical passageways, the disks '70 to 116 are numbered consecutively as shown in Fig. 3 and Figs. 5 to 51 and are shown consecutively in the drawings. Each disk has six small apertures through which fastening members 117 extend and hold the assembled disks in proper relation. A number of the disks have three sectors cut out of the periphery thereof, which sectors are aligned in the stack to form longitudinal venting passageways 118. As the contact passageway 32 extends downward from the pressure chamber 44, vents 119 from the contact passageway 32 to the longitudinal venting passageways 118 are provided at intervals as shown in disks 77, 78, 81, 82, 85, 86, 89, 96, etc.

As the helical fluid supply passageways extend from the pressure chamber 44, these passageways decrease in cross section.

Figs. 3 and 4 illustrate the preferred form of the present invention, in which the passageways 120 form an array coaxial with the contact passageway 32 and are of stepped decreasing cross section. These passageways 120 impel and divert liquid into the arc along the length of the arc drawn in the contact passageway 32. While Fig. 2 illustrates but two such passageways arranged in helixes around the contact passageway 32, such showing is merely illustrative of the preferred embodiment, for the number of the pasageways, the length, cross section, and the change in cross section per unit length, and the pitch, pitch diameter, and positioning of the helical passageways may be varied by the design, dependent upon current and voltage conditions and the type of service for which any particular circuit breaker is to be used.

Operation of the embodiment illustrated in Fig. 2 is as follows. Downward movement of the movable contact 14 draws an are between such contact and the fixed contact 13 in the pressure generating chamber 44. The are breaks down a portion of the arc extinguishing liquid, thereby generating a pressure which is immediately transmitted to the columns of liquid in the helical passages 120. The cross section and pitch of the helical passages 120 are selected to give a relatively low flow resistance to the column of liquid and, therefore, the pressure exerted from the pressure chamber on the top of the liquid column, forces a stream of liquid rapidly down each helical passageway 120. The stepped reduction in volume of the helical passageways 120 results in a positive and continuous diversion of liquid from each of the columns into the contact passageway 32 throughout its effective length.

The shape and volume of the helical passageways 120 and the proportioning of the openings from the helical passageways 129 into the contact passage 32 are such as to deter the products of decomposition from entering the helical passageways 120 and adversely reacting on the liquid therein. The particular construction of the helical passageway 120 affords exposure of only a limited quantity of the fluid in the passageways to the arc in the contact passageway 32. For the purposes of explanation, the configuration of the liquid in thepassageway 120 may be considered to be substantially in the form of a helical wedge with the upper or driving surface of the wedge exposed to the liquid in the pressure generating chamber 44, and the apex portion of the wedge extending into the openings of the disks 116. Pressure exerted from the pressure generating chamber 44 upon the upper portion of the wedge-shaped column of liquid in the passageway 120, will force the wedge of liquid downward along the tapering passageway 120. As the column of liquid moves downward the surface of the walls of the passageways react on it so as to force those portions of the liquid adjacent to the contact passageway 32 into the are contained therein along the entire length of the arc, with the result that the arc is exposed to a progressively developing front of substantially uncontaminated and un-ionized liquid. Thus, relatively un-ionized liquid is continuously, progressively and forcibly delivered along two continuous and progressively developing helical fronts and is forcibly impelled into the are as it is extended in the contact passageway 32.

At various intervals, the excess ionized gas in the arcing region in the contact passageway 32 is vented through the vents 118, 119 to the space outside of the unit, where it is dispersed without mixing such ionized gases with the liquid in the helical passageways 120 that is utilized for arc extinguishment.

In accordance with the invention claimed the contact passageway or are passage 32 is defined by a wall structure extending generally longitudinally of and partially circumferentially surrounding the common axis of contacts 13 and 14. A second wall structure defines the fluid supply passageway 120. Passageway 120 is of progressively varying transverse cross sectional area. The axis of passageway 120 is spaced laterally from the axis of the arc passage 32. The wall structures provide a common longitudinal opening 129 for the flow of fluid from the fluid supply passageway 120 to the arc passage 32.

Arc restraining means such as grids 130 are provided in the common opening 129 at diflerent points around the circumference of arc passage 32 along its longitudinal axis to restrict or restrain the are from moving from passage 32 into passageway 120. Grids 130 consist of bars forming parts of plates 93 and others of a similar type and are used to center the arc in passage 32. These are centering or oil deflecting bars hold the are close to the longitudinal axis of the stack to deflect oil out of the helical passageways 120 into the central contact passage 32 and to provide oil soaked structural elements which are as close as possible to the core of the arc.

Barrier plates 74 and 75 and all others of similar design are called insulating inlet plates and are provided with a pair of diametrically positioned inlet passages 131 on one level so that an incoming flow of fluid may pass through the inlet passages 131 from supply passageways 120 inwardly toward the are substantially transversely thereto on opposite sides thereof.

Barrier plates such as plates of the type shown in Figs. 52 and 53 may be called inlet plates having one inlet passage 131 blocked or partially blocked by the grid 13% so that the grid restricts the are from moving into passageways 120 but still permits some of the fluid to pass therethrough. As shown in Figs. 8, 9 and 10 the central apertures are parts of the passageway 32. The aperture of the plate shown in Fig. 9 has a larger diameter than the two contiguous plates shown in Figs. 8 and 10. The central aperture in Fig. 9 has a tendency to reduce the velocity of oil flow therethrough.

While the circuit breaker is opening the arcing surface 33 of the movable contact 14 passes the resistor electrode 48 before passing through nozzle 55. Part of the body of contact 14 moves through the nozzle during interruption of the power are. Immediately after momentary interruption at a current zero the returning voltage between contacts 13 and 14 causes current to flow through the resistor assembly 45 because the voltage breaks down the gap at one or more of the probes 53 of resistor electrode 43 (due to the short gap between the electrode 48 and the body of contact 14 as compared with the main interrupting gap between surface 33 and contact 13). The resistor assembly 45 is thereby inserted in series with the power circuit through an auxiliary are so that the resistance circuit now shunts the contacts 14, 16 and 13.

In the device shown in the drawing the arc must be extinguished in the upper portion of assembly 36 to assure the normal interrupting time of five cycles for this circuit breaker. Such quick extinction of the interrupting arc is accomplished by the turbulent flow or blast in the upper helical passages and the spaced lateral vents 119. Vents 119 discharge through the vertical manifold or venting passages 118 through exhaust ports 15!) to the surrounding oil in tank 2.

If the resistor assembly 45 is to be efiective in extinguishing the power are, it must be inserted in the circuit to electrically shunt the arc or arcs shortly after separation of the arcing contacts.

In this invention that small portion of the ionized gas and oil mixture which is diverted from the zone of arc initiation and impelled downward along the central passageway 32 in advance of the downward movement of the movable contact arcing tip 33 is utilized to insert the resistance of resistor assembly 45 in the power circuit. The new and improved probe electrode 48 may provide a plurality of probes so arranged as not to impede the flow of oil or gas through electrode 48 but at the same time to provide a plurality of small discharge gaps between the body of contact 14 and the ends of the probes closest thereto which completely surround the movable contact and which will break down under the stress of the impressed arc volt-age to electrically connect the resistor assembly 45 to the movable contact 14.

It is only for the purpose of extinguishing the resistance current are which persists after extinction of the interrupting are that a blast of ionized gas or oil is expelled from the lower extremity of passageway 32. through nozzle 55 forming opening 56 as the movable arcing contact tip 33 emerges therefrom in its downward movement.

The magnitude of the arc current is correspondingly decreased by the resistance and the difliculty of completely interrupting the current is greatly diminished, particularly in the case of circuits having high rates of increases of the recovery voltage and also in the case of capacitance switching. The ohmic value of the resistance 45 depends on the characteristics of the circuit to be controlled.

When the comparatively weak arc current through the resistor is finally extinguished by the cooling eflect of the oil, further downward movement of contact 14 serves to increase the oil gap for isolating the contacts from each other so that there is no danger of flashover or restriking of the arc.

The present invention as embodied in the device of Fig. 1, therefore, provides a unique and highly effective multiple front helical impulsion of fresh liquid into the are from all angles and elevations as the are is extended in the contact passageway 32. This all-over attack is started at the earliest eflective time and continues throughout existence of the arc. This arc extinguishing action is efiected not only from all angles and all elevations but also by various arc extinguishing action including turbulence, displacement, diffusion, dilution and ion recombination. The configuration and relative positioning of the passageways 120, as above described, is such as to effectively maintain the integrity of the liquid in said passageways and to provide for the diversion of the liquid into the passageway 32 when pressure is exerted on the top of the column of liquid in the passageway 120. Further, the openings 118, 119 provide for side evacuation of the contaminated liquid and are products from the arcing region in the passageway 32 to the space outside of the arc extinguishing device 1.

Thus, an eflicient, simple and compact interrupting unit is provided that occupies practically no more space within the oil tank than a conventional interrupting chamber and that is easy to inspect or repair. The resistor unit can be readily removed from the breaker and replaced independently of the chamber and the contacts therein so that complete disassembly of the chamber construction is unnecessary.

Although but one embodiment of the present invention has been illustrated and described, it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit of the invention or from the scope of the appended claims.

It is claimed and desired to secure by Letters Patent:

1. In a circuit interrupter, means for establishing an arc, means including a plurality of contiguously disposed insulating plates forming a stack for defining a substantially enclosed arc passage for confining the are along a major portion of its length, said plates comprising a plurality of insulating inlet plates, each said inlet plate providing a pair of diametrically positioned inlet passages on one level so that an incoming flow of fluid may pass through the inlet passages inwardly toward the are substantially transversely thereto on opposite sides thereof, the arc passage openings of alternately arranged inlet plates having diflerent dimensions.

2. In a circuit interrupter, means for establishing an are, means including a plurality of contiguously disposed insulating plates forming a stack for defining a substantially enclosed arc passage for confining the are along a major portion of its length, said plates comprising a series of three insulating inlet plates, each said inlet plate providing a pair of diametrically positioned inlet passages on one level so that an incoming flow of fluid may pass through the inlet passages inwardly toward the are substantially transversely thereto on opposite sides thereof, the arc passage opening of the middle inlet plate having a larger diameter than the other two contiguous inlet plates.

3. In a circuit interrupter, means for establishing an arc, means including a plurality of contiguously disposed insulating plates forming a stack for defining a substantially enclosed arc passage for confining the are along a major portion of its length, said plates comprising a plurality of insulating dual purpose plates each providing inlet and outlet passages on one level so that an incoming flow of fluid may pass through the inlet passage inwardly toward the are substantially transversely thereto and through the outlet passage, the arc passage opening of alternately arranged dual purpose plates having ditferent dimensions.

4. In a circuit interrupter, means for establishing an arc, means including a plurality of contiguously disposed insulating plates forming a stack for defining a substantially enclosed arc passage for confining the are along a major portion of its length, said plates comprising a plurality of insulating dual plates each providing inlet and outlet passages on one level so that an incoming flow of fluid may pass through the inlet passages inwardly toward the are substantially transversely thereto and through the outlet passage, the arc passage openings of contiguously arranged dual purpose plates having diflerent dimensions.

5. In a circuit breaker: an arc extinguishing device immersed in arc extinguishing fluid, a pressure generating chamber in said device, a stack of barrier plates of insulating material pressed together and disposed adjacent to said pressure chamber, said plates having aligned openings therethrough to provide an elongated arc passage, means for drawing an arc in said pressure generating chamber, said means comprising relatively movable contacts one of which is withdrawable through said are passage to extend said are, said are passage being defined by a first wall structure of said barrier plates extending generally longitudinally of and partially circumferentially surrounding the common axis of said contacts, said barrier plates defining a second wall structure which defines at least one fluid confining passageway of progressively varying transverse cross sectional area, the axis of said fluid confining passageway being spaced laterally from the axis of said are passage, said fluid confining passageway extending generally longitudinally of the axis of said are passage from said pressure generating chamber along at least a portion of the length of said are passage, said barrier plates comprising inlet plates disposed throughout the stack and providing a pair of diametrically positioned inlet passages on one level so that the flow of fluid passing through the fluid confining passageway may flow through the inlet passages inwardly into the arc passage substantially transversely thereto on opposite sides thereof, said inlet barrier plates providing contact opening of different dimensions.

6. In a circuit breaker: an arc extinguishing device immersed in arc extinguishing fluid, a pressure generating chamber in said device, a stack of barrier plates of insulating material pressed together and disposed adjacent to said pressure chamber, said plates having aligned openings therethrough to provide an elongated arc passage, means for drawing an arc in said pressure generating chamber, said means comprising relatively movable contacts one of which is withdrawable through said are passage to extend said arc, said are passage being defined by a first wall structure of said barrier plates extending generally longitudinally of and partially circumferentially surrounding the common axis of said contacts, said barrier plates defining a second wall structure which defines at least one fluid confining passageway of progressively varying transverse cross sectional area, the axis of said fluid confining passageway being spaced laterally from the axis of said are passage, said fluid confining passageway extending generally longitudinally of the axis of said are passage from said pressure generating chamber along at least a portion of the length of said are passage, said barrier plates comprising dual purpose plates disposed throughout the stack and each providing inlet and outlet passages on one level so that the flow of fluid passing through the fluid confining passageway may flow through the inlet passages inwardly into the arc passage substantially transversely thereto and through the outlet passage, said dual purpose barrier plates providing contact openings of different dimensions.

7. In a circuit interrupter, means for establishing an arc, means including a plurality of contiguously disposed insulating plates for defining a substantially enclosed arc passage for confining the are along a major portion of its length, said means comprising a plurality of insulating inlet plates providing a pair of diametrically positioned inlet passages on one level so that an incoming flow of fluid may pass through the inlet passages inwardly toward the are substantially transversely thereto on opposite sides thereof, and dual purpose grid means arranged across one inlet passage of a number of said inlet plates to restrict the flow of fluid through said inlet passages and to hold the are close to the longitudinal axis of said stack.

8. In a circuit interrupter, means for establishing an arc, means including a plurality of contiguously disposed insulating plates for defining a substantially enclosed arc passage for confining the are along a major portion of its length, said means comprising a plurality of insulating inlet plates providing a pair of diametrically positioned inlet passages on one level so that an incoming flow of fluid may pass through the inlet passages in wardly toward the are substantially transversely thereto on opposite sides thereof, the contact opening of alternately arranged inlet plates having different dimensions, and dual purpose grid means arranged across one inlet passage of a number of said inlet plates to restrict the flow of fluid through said inlet passages and to hold the are close to the longitudinal axis of said stack.

9, In a circuit breaker; an arc extinguishing device 10 immersed in arc extinguishing fluid, a stack of barrier plates of insulating material pressed together and arranged in said device, said plates having aligned openings therethrough to provide an elongated arc passage, means for drawing an arc in said are passage, said means comprising relatively movable contacts one of which is withdrawable through said are passage to extend said arc, said are passage being defined by a first wall structure of said barrier plates extending generally longitudinally of and partially circumferentially surrounding the common axis of said contacts, said barrier plates comprising a second wall structure which defines a fluid supply passageway, the axis of said fluid supply passageway being spaced laterally from the axis of said arc passage, said barrier plates comprising inlet plates disposed throughout the stack and providing a pair of diametrically positioned inlet passages on one level so that the flow of fluid passing through the fluid supply passageway may flow through the inlet passages inwardly intothe arc passage substantially transversely thereto on opposite sides thereof, and means arranged across a number of said inlet passages to hold the are close to the longitudinal axis of said stack.

10. In a circuit breaker; an arc extinguishing device immersed in arc extinguishing fluid, a stack of barrier plates of insulating material pressed together and arranged in said device, said plates having aligned openings therethrough to provide an elongated arc passage, means for drawing an arc in said are passage, said means comprising relatively movable contacts one of which is withdrawaole through said are passage to extend said arc, said are passage being defined by a first wall structure of said barrier plates extending generally longitudinally of and partially circumferentially surrounding the common axis of said contacts, said barrier plates defining a second wall structure which defines a fluid supply passageway, the axis of said fluid supply passageway being spaced laterally from the axis of said are passage, said barrier plates comprising inlet plates disposed throughout the stack and providing a pair of diametrically positioned inlet passages on one level so that the flow of fluid passing through the fluid supply passageway may flow through the inlet passages inwardly into the arc passage substantially transversely thereto on opposite sides thereof, and dual purpose barrier means arranged across a number of said inlet passages to restrict the flow of fluid through said inlet passages and to restrain the are from moving in said are passage.

11. In a circuit breaker; an arc extinguishing device immersed in arc extinguishing fluid, a stack of barrier plates of insulating material pressed together and arranged in said device, said plates having aligned openings therethrough to provide an elongated arc passage, means for drawing an arc in said are passage, said means comprising relatively movable contacts one of which is withdrawable through said are passage to extend said arc, said are passage being defined by a first wall structure of said barrier plates extending generally longitudinally of and partially circumferentially surrounding the common axis of said contacts, said barrier plates defining a second wall structure which defines a fluid supply passageway, the axis of. said fluid supply passageway being spaced laterally from and longitudinally of the axis of said are passage, said barrier plates comprising inlet plates disposed throughout the stack and providing a pair of diametrically positioned inlet passages on one level so that the flow of fluid passing through the fluid supply passageway may flow through the inlet passages inwardly into the are passage substantially transversely thereto on opposite sides thereof, and grid means arranged across one inlet passage of a number of said inlet plates to restrict the flow of fluid through said inlet passages and to hold the arc close to the longitudinal axis of said stack.

12. In a circuit breaker; an arc extinguishing device immersed in arc extinguishing fluid, a stack of barrier plates of insulating material pressed together and arranged in said device, said plates having aligned openings there through to provide an elongated arc passage, means for drawing an arc in said arc passage, said means comprising relatively movable contacts one of which is withdrawable through said arc passage to extend said arc, said are passage being defined by a first wall structure of said barrier plates extending generally longitudinally of and partially circumferentially surrounding the common axis of said contacts, said barrier plates comprising a second wall structure which defines a fluid supply passageway, the axis of said fluid supply passageway being spaced laterally from and longitudinally of the axis of said are passage, said barrier plates comprising inlet plates disposed throughout the stack and providing a pair of diametrically positioned inlet passages on one level so that the fiow of fluid passing through the fluid supply passageway may flow through the inlet passages inwardly into the arc References Cited in the file of this patent UNITED STATES PATENTS 2,445,442 Leeds et al. July 20, 1948 2,452,477 Leeds Oct. 26, 1948 2,467,542 Taylor Apr. 19, 1949 2,467,760 Ludwig et al Apr. 19, 1949 2,473,844 Baker et a1. June 21, 1949 2,539,175 Balentine Jan, 23, 1951 2,545,334 Balentine Mar. 13, 1951 

